Process for treating bydrocarbon oils



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Patented June 28, 1932 UNITED STATES PATENT OFFICE CARBON P. DUBBS, OF CHICAGO, ILLINOIS Assienon To Uiviviain'sai.r oir. rnonuo'rs PROCESS FOR TREATING HYDROGARBON OILS .application led April 9, 1927. Serial No. 182,205.

rIhis invention relates to a method for treating hydrocarbon oils to produce therefrom products of lower boiling points.

rl`liis application is in part a continuation of an application Serial Number 523,113, filed December 17, 1921, itself in part a continuation of an application Serial Number 204,527, filed November 30, 1917. Divided and application 266,398 iiled Dec. 12, 1918. Renewed June 16, 1923. Matured into Patent No. 1,543,831.

Among the salient objects of the invention are to provide an improved process in wliic the heated hydrocarbons are circulated then passed to a condenser, and during such treatment subjected to the pressure of the generated vapors; to provide a process in which the temperature and pressure are readily and accurately oo nprocess wherein the circulation of the hydrocarbons being treated is readily and accurately controlled; to provide a process which can be operated continuously; to provide a process which avoids 'f3 the danger of the tubes in which the hydrocarbon is heating from being burned out by preventing the precipitation of carbon on said tubes, this being accomplished by means of the rapid circulation of the oil through "i said tubes; to provide a process in which such products that are only partly converted to the desired low boiling point are returned and further treated in the distilling tubes;

by means of aircooled condenser, the grade of distillate allowed to pass from .the system is controlled, and such distillate not up to a desired grade is condensed and automatically returned to distilling coils and redistilled; to provide a process in which the heating tubes and the distilling tubes are maintained in a furnace held within well defined temperature ranges, and the oil caused to circulate through said l., heating tubes at such velocity as to prevent any great amount of carbon depositing on said tubes; and, in general, to provide an improved process of the character referred to.

In the drawings: Fig. 1 and Fig. 1a together show a side elevation partly in section and with other parts broken away.

Fig. 1b is a side view ofthe liquidv level regulator and diaphragm valve, shown in fragmentary section.

Fig. 2 and Fig. 2a are a plan view of .the construction shown in Figs. 1 and la.

Fig. 3 is an end elevation of the condensing members.

Fig. 4 is a view, partly in elevation and partly in section of the heating coils.

Referring to tie drawings, A-l are the furnaces in which the heating tubes and distilling tubes are positioned. A-2 are the tunnels through which the fire for heating the furnaces passes. A-3 are the furnace flues. A-4 is the iue stack.

B-l constitute parallel substantially level heating tubes, and B-2 constitute substantially level distilling tubes. B-3,

B-4, B- and B-6 are return Ts on the heating tubes. B-7, B-S and B-S) are fittings around the tubes for anchoring the particular tube shown. All the tubes extend through the furnace walls and are free to eX- pand independently thereof, with the exception of where the two tubes are anchored. B-lG and B-17 are braces for supporting the tubes B-l and B-2.

@-1 is a feed line from any source of supply to pump @-2, and in this line is tlirotg tlc valve @-3. @-4 is the charging line from the pump to the heating tubes B-l, and in this line is the throttle valve @-5. @-6 and @-7 are motors for operating the pumps @-2 and @-8. which is supplied through line @-9 branch ing from the suction line @-1. @-10 is the discharge line connecting this pump with charging line @-4, and branching off of discharge line @-10 is a branch line @-11 which connects with suction line @-9 and having positioned on it a' pressure relief valve or by-pass valve @-12. @-13 is a gas nieter of any standard make suitable for the work in hand. @-14 is a standard make check-valve. There is shown generally at @-15 an automatic yliquid level regulating gauge. The one shown is that furnished by the S-c Regulator Company of Fostoria,

@-8 is a pump' Ohio. This automatic liquid level gauge controls the valve O-l6 in the supply line O-4 through the medium of the diaphragm O-l7. This automatic liquid level gauge comprises an outer casing Z surrounding a tube Z-l, the casing Z forming an annuular space about the tube Z-l. A suitable liquid,

such as water, is supplied to the casing Z.

The tube Z-l is connected to the vertical line Z-Qthrough the connectionsZ-S and 2 4. The vertical line Z-2 is connected to one end of dist-illing tube B-Q through the medium of the transverse vertically spaced lines Z-. One of these lines Z- communicates with the distilling tube B-Q above the maximum liquid level desired to be maintained in the distilling tube and the other line Z- communicates with the distilling tube below the minimum liquid level desired to be maintained in the distilling tube. The result is that vapors pass from thedistilling tube B-2 to the vertical line Z-Q through the upper transverse line Z- while liquid passes to the vertical line Z-2 through the lower transverse line Z-. It is to be noted that the casing Z is :positioned at an angle with respect to the vertical and'is so arranged that its upper end is above the maximum liquid level desired to be maintained in the distilling tube B-Q and its -lower end below the minimum liquid level desired to be maintained in the distilling tube B-Q. The operation of the device is as follows:

Ordinarily the liquid level will be maintained at about the middle height of the distilling tube B-Q. The liquid will therefore fill the lower end of the line Z-2 and the connecting line Z-4. The exposed area between the lower transverse line Z-5 `and the lower end of the tube Z-l is suchthat the liquid oil will be materially cooled before it reaches the tube Z-l. The vapors, on the other hand, are delivered through the upper tube Z-5 and connecting line Z-3 to the upper end of the tube Z-l without material cooling. It will thus be seen that a portion of the tube Z-l is filled with liquid oil and a portion thereof with vapors at a higher temperature t-han the liquid oil. As the liquid level in the distilling tubes B-2 changes, the length of the tube Z-l occupied by the liquid oil also changes. When the liquid level raises in the distilling tubes B-Q and the relatively cool liquid oil raises in the tube Z-l the temperature of the expansive fluid in the annular space between the tube Z-l and the casing Zv decreases and the liquid, such as water, contracts and releases the pressure on the diaphragm C-17 thus causing the valve @-16 to move toward closed position. On the other hand, if the liquid level in the distilling tubes B-.Q is temporarily lowered, the

level of the liquid in the tube Z*l is also lowered, thus a greater length of the tube Z-*l is occupied by the hot vapors and the temperature of the liquid in the casing Z is thus increased with the result that this liquid expands and imparts pressure to the diaphragm O-l' through the line Z-G car ing valve C-lG to move toward open position thus admitting more oil to the process.

B-lO is a fitting connecting adjacent heating tube B-l to the supply line 0 4. B-ll is the fitting on the end of heating tubes B-l through which the oil in same is discharged into line D-l. I he line D-l is connected to the bottom of the fitting B--l2, which is secured to the distilling tubes The oil is discharged out through the bottom of the litting B-ll by means of the line E-l and through cooling tank "Ef-2, and then to any suitable storage, not shown, and between said storage and cooling tank E-Q is positioned, in line Ehi, a throttle valve E-S to control the rate of iiow of the residuum through the line Elg and a similar valve, marked E-/l, is positioned in the line E-l for obtaining samples of the residuum Howing through the line E-l.

F -l is a centrifugal pump. F-Q is amo tor for operating same. F-3 is the suction line to the pump from the heatingy tubes B-l which comes out of the bottom of the fitting marked BG. F`/l is the discharge line which enters the side of the fitting marked 13h10 on the end of the heating tubes marked B-l. F`5 isv a'carbon trap on the end of `the distilling coils attached to the bottom of the fitting marked B-l3- G-l, G-Q, G-S and G-4 are upwardlv inclined vapor lines leading on of the distill-.

ing tubes B-Q. f Lines G-l and G-4 connect with a manifold G-5, which manifold connects by pipe G-t to fitting B-S attached to the distilling tubes Lines G`2 and @1*8 connectto a manifold G-'T, which manifold connects, by means of pipe G-8, to the top of fitting B-.l3 'on the'end of the distilling tubes Bh. Taese vapor lines G-l, G-2, G*3 and G-f-l are connected at their upper ends to a common header (Jl- 9, and have positioned en them throttle valves G-l0, Cir-ll, G-lQ and G`l3. Said manifold G Q is connected to atop manifold G-lt by means of bent pipesl G-l to G`26, and to the center of the top manifold G-M is connected pipe G-Q? which connects, in turn, to the coil (24*28 contained in the water tank G QQ. From the coils G-28 the condenser extends through pipe G-3O into the receiving tank H. Freni the pipe G-30 is a branch pipe iff-31 having a pressure indicating gauge (ii- 32, and out of the valve (nl-3l extends pipe G-BB on the end of which is a valve (TIL-34. This valve and gauge may be situated in 'the taill house and afford means for the pressure.

On the tank H are glass liquid gauges Hhl there regulating and Irl-2, pressure relief valve H-S, draw valves H-Jl, H- and lit-6, and pressure gauge H-7. H-G is for use in case water is to be drawn off before draining the distillate out through the valve H-. H-Ll is a valve for use in an emergency, for example: when one of the other valves is removed for repairl or renewal, and which valve is superiicial for showing the workings of the apparatus.

J-l, J-Q and J-S are supports for the receiving tank H. K is a support for the pipes shown.

L-l is a standard indicating pyrometer and is connected with different thermosticks, which thermosticks are positioned in the furnace in which the tubes B-l and B-2 are positioned. L-2 is a standard temperature recording instrument and is connected to a thermostick by a cable, and which thermostick is positioned inside the manifold G-'lt L-S is a standard temperature recording instrument connected, by means of a cable, to thermosticks, which latter are positioned, one in the heating coils, to give the temperature of the oil contained therein, and one positioned in the large distilling coils, to give the temperature of the oil contained therein. L--t is a standard indicating liquid gauge which is connected by tubing to the receiving tank H and shows the depth of the liquid contained in the receiving tank H. lil-5 is an electric switchboard of standard make, which board contains the standard knife switch for breaking or completing the circuit in operating the charging pump @-2; also a knife switch for breaking or completing the electric circuit for controlling the motor @-6 which operates the circulating` pump @-S; also a knife switch for breaking or completing the electric circuit for controlling the electric circulating pump F-l, also a knife switch of standard make for breaking or completing the electric current for supplying the electric lights in the plant, all

of which are enclosed in the house built beneath the water cooling tank @-29.

M-l is the gas main for supplying the furnace in which the tubes B-l and B-Q are contained. and on this line is positioned throttle valve M-Q.

N-l, N-Q, N-S and lil- 4f are supports for the extensions O-l and O-Q, which eX- tensions are simply housing over the ends of the heating tubes B-l and the distilling tubes B-EZ, which housing is to prevent more or less cooling effect that would be caused by leaving them open to the atmosphere, and also to prevent subjecting the ends to varying temperatures.

Describing now the operation of the process, the material to be treated is drawn from any suitable source of supply through the line @-1, by and through centrifugal pump @-2, through line @-4 into the heating tubes B-l, then through line D-i to distilling tubes B-2, and when these latter heating tubes have been filled to desired level, pump @-2 is shut down and valve @-3 on line @-1 and valve @-5 on line @-4 are closed, and normally remain closed on the rest of the run. Heat is applied to the furnace A-l, and as soon as a desired vapor pressure has been created on the apparatus then. supply pump @-8 is started in operation and obtains its supply of raw material through line @-9 and discharges through line @-10 into line @-4, valve @-18 being opened; and should the level of the liquid in the distilling tubes B-Q be of the proper height, then the liquid level regulator @-15 will, by means of diaphragm @-ll', close the valve @-16 on the supply line @-4, and the back pressure thus created on the line @-4 will force open the pressure relief valve @-l2 and by-pass the oil from the discharge side of the pump @-8 back into the suction line @-9, and this operation will continue until the level in the distillate tubes B-2 drops to a suiiicient point to permit the valve @-16 to be automatically opened, thus admitting more raw material into the heating tubes B-l and B-2.

rlhe pump lT-l is put and maintained in operation, and the oil in the heating tubes B-l made to circulate by drawing the oil through suction lT-S and discharge back into the tubes through discharge F-4.

The residu-.uni formed in the distilling tubes B-2 can be drawn olf either intermittently or continuously through line E-l through cooling coil contained in tank lil-2' and from there to any suitable storage. The quantity that is drawn off is regulated by means of valve E-S positioned in line lll-l, and samples of said residuum may be. obtained at any time through valve l-i in line E-l.

rlhe vapors generated pass u p through lines G-l, G-Q, G-3 and G-et and into manifold (3f-9, and from there out through pipes (tl-15 to @-26 and into manifold G-lt. All the vapors that are condensed up to this point are drained back into the distilling tubes B-2, while the remaining vapors pass through. line (3l-2?, through cooling coils (3v-29 immersed in water in tank @-29, and from there pass through line G-SO into receiving tank H, from which they may be drawn o intermittently or continuously through valves H- and Irl-6.

It will be seen that this method provides a process for automatically and continuously treating petroleum for the production of lower boiling point products, and by means of the circulation of the liquid into heating tubes B-l permits of the furnace in which the tubes are positioned beingl maintained at a considerably higher heat without injurious effect to the oil, and prevents any substantial deposit of carbon on the tubes.

The method while disclosed as being operated with a liquid level regulator, may be as easily operated and in some cases preferably, by disconnecting the liquid level regulator and introducing fresh oil from time to time as the operator desires. In certain cases Where a certain liquid level is maintained in the vaporizing chamber, the conditions of cracking cannot be maintained properly and it is necessary at times to either raise the liquid level or allow it to lower to a point Where more desirable and advantageous conditions of cracking are obtained. Also, the local circulation which is maintained in the heating zone through the pump F-1 during the operation of the process, may be functioned during the initial stages to raise the oi-l to a cracking temperature before passing it to the distilling zone, that is, by circulating the oil only through the heating zone during the initial heating, it is possible to raise the oil quicker to the desired temperature than Where a greater quantity of oil is to be heated and the same must pass continuously through the entire system.

The entire system is preferably subjected to a vapor pressure of from to 500 lbs., although the pressure Will vary with the conditions. The temperature of the oil Will preferably vary from 500 to 1000O F., although I do not limit myself to these figures. The pump is preferably operated so as to cause a relatively rapid circulation of the oil in the heating tubes.

It will be readily seen that since the liquid level regulator will tend to maintain a constant level in the distilling tubes B-Q and therethrough the constant amount of feed oil charged into the process through line 0 4, the automatic control will therefore regulate also the temperature of the oil leaving the tubes B-1 and this Will be of great advantage in maintaining the. conditions of cracking to a nicety and obtaining improved results.

I claim as my invention:

1. A process for cracking hydrocarbon oil comprising heating the oil in a heating zone, thereafter delivering the heated oil to a distilling zone, maintaining a superatmospheric pressure on oil in said heating and distilling zones, continuously removing vapors from said distilling zone, continuously advancing a constant volume of charging oil for the `process in a stream from the outlet of a mechanical pressure applying means, maintaining a constant volume. of oil in said distilling zone by automatically regulating the amount of oil admitted from said stream to m said heating zone through the medium of thermal means responsive to changes in the liquid level of the oil body in said distilling zone and directly returning such portions of said oil stream as are not admitted to said heating zone to the inlet side. of said mechanical pressure applying means.

2. A method for maintaining a constant volume of oil under a superatmospherlc pressure 1n the distilling zone 01"' an oil cracking apparatus which comprises continuously advancing a constant volume of charging oil in a stream from the outlet of a mechanical pressure applying device, admitting a portion of the oil from said stream into the cracking apparatus, returning the remaining ingv apparatus through the medium of therl,

mal means responsive to changes in the liquid level of the oil in the distillng zone of the oil cracking apparatus.

CARBON P. DUBBS. 

